Growing Hardy Bulbs

By Jan Cashman • Posted on September, 1st 2010

By Bonnie Hickey

The majority of hardy bulbs we grow in Montana originated in the Mediterranean or areas of similar climate, which have wet winters and dry summers. These plants grow and flower during periods of good weather and then go dormant to survive inhospitable periods. Understanding the bulb’s preferences is the key to success in growing bulbs. These expectations are fairly simple, making bulbs one of the easiest flowering plants to grow.

Soil Prep and Planting

Generally, bulbs should be planted no sooner than 6 weeks before frost. Exceptions are Colchicum, Lilies, Fritillaria, Erythronium, which should be planted as soon as received. They prefer a sunny location (remember – what is shady now may not be in the spring, if the shade is caused by deciduous trees). They also require a well draining soil.

If you will be planting a lot of bulbs in an area, begin by loosening the soil to a depth of 12 inches. Top the soil with 1 inch compost and 2 inches of peat moss. If your soil is heavy clay, also add 2 inches of soil pep or sand to improve aeration and drainage. Blend the amendments into the loosened soil.

For larger bulbs such as tulips and daffodils, remove the soil from the planting spot to a depth of 8 inches. Work bone meal into the soil at the bottom of the hole (2 tbsp/ 1 sq ft, 10 lb/ 250 sq ft). Set the bulbs pointed end up in the bottom of the hole. Space tulips 4-6” apart and daffodils 6-8” apart. Cover with soil and water in well.

Follow the same procedure for other bulbs, planting the bulbs at a depth that is 3-4 times the bulb size (Crocus at 3”, etc.).

Further Care

Once the bulb’s leaves emerge from the ground in the spring, top dress with a balanced granular fertilizer such as a 17/17/17. Remove spent flowers to prolong bloom and preserve strength. Allow the leaves to ripen fully before removing. They will turn yellow or brown and will readily pull free when they are ripe. This takes about 6 weeks.

Many bulbs will multiply and the clump will get larger and showier with each passing year. Eventually, you may want to dig the bulbs and divide them in the summer to start new clumps. Mark their location so that you can find them in the summer. Other bulbs are shorter lived and their flower show will begin to decline, such as tulips. In this case, don’t wait for the foliage to ripen. When they are done blooming, pull them up immediately, while you know where they are.

Grape Hyacinth (Muscari armeniacum) grows leaves in the spring while it is flowering and again in the fall. Fall crocus (Colchicum) will grow large tulip size leaves in the spring, which will then disappear. The lavender blooms then rise from the ground in fall, as the rest of the garden goes to sleep.

Bulb Combinations

Large sweeps of a single type and color of bulb will have high impact. Example: A mass of red Apeldoorn tulip behind an equal mass of King Alfred type daffodil would be a sure attention getter. A sweep of grape hyacinth or Siberian squill through a garden might simulate a meandering brook. Another look, best seen close up, can be had by custom mixing tulip colors in one planting hole: pink, white, lavender is sweet; black/purple and white is elegant; white, pink and rose red is very rich, or choose a pastel mix of pink, apricot, and soft yellow.

Under plant tulips or daffodils with a smaller bulb such as chionodoxa or squill for a layered look. Create custom blends in your favorite colors, or choose colors that coordinate with your interior if you will be cutting blooms for bouquets.

Early to mid spring bulbs can be planted between clumps of perennials. The perennials foliage will grow up and hide the bulb foliage while it passes, plus your perennial garden space gains early color.

Plant under trees and between shrubs for spring color. Bulbs will get the sun they need because the trees and shrubs will not have leafed out. Squill is one of the few bulbs to do well in shade.

Plant bulbs in the spots where you will later be planting annuals. The bulbs will be deep enough to be out of the way. Choose early to mid season bulbs whose foliage ripens quickly (Triumph Tulips work well).

Tall late tulips are great in the back of annual or perennial beds. Their foliage takes a long time to ripen, but will be hidden by the other plants.

Naturalizing

This refers to planting bulbs in your yard as though they grew there naturally. You will need to choose bulbs that are especially hardy, ones that multiply readily. Choices might include Chionodoxa, Colchicum, Crocus, Muscari, Squill, all types of Daffodils, species Tulip, Erythronium, Species Iris, and Alliums.

Bulbs can be planted throughout the lawn. In areas you will want to begin mowing in late spring, choose early bulbs like Siberian Squill or Crocus. Daffodils are spectacular in a lawn, but you won’t be able to mow for a while. You might try putting them along an edge that you can hold off on mowing or plant them out in an area of rough grass or wildflowers that won’t be mowed till later.

One effect is to select a mixture of bulbs, scatter by hand and plant them where they fall. Or – select 2-3 varieties but do not mix. Scatter and plant one variety in a drift, followed by the next variety, to create a tapestry. Small bulbs are easily planted with two people, if one person digs in with the shovel and pries forward while the other person tucks the bulbs behind the shovel blade. Then stomp the soil back into place.

Don’t miss planting within groves of aspen or birch. Masses of one taller flower and one lower flower have the most impact.

What Are Bulbs?

We use the name loosely to apply to a variety of spring or fall planted flowers. By definition, we separate these plants into the following groups.

Bulbs

Layers of modified leaves surrounding a flower bud. Stems are produced from the base each year until its strength is used up. Includes Tulips, Hyacinths, Daffodils, Lilies, and Alliums. Propagated by bulblets, which develop off the basal plate. Keep the bulblets and discard old bulbs. Bulblets will not bloom for several years. With Daffodils you can replant the parent bulb.

Corms

Solid, with no differentiation of tissue. Stems grow from the top and produce offsets to multiply. Includes Crocus, Colchicum.

Tuber

A section of underground stem, swollen with stored nutrients. It develops growth buds or eyes along its surface. Includes Winter Aconites, Anemones, potatoes. Propagate by divisions containing at least three eyes.

Rhizomes

Thickened storage stems growing horizontally below the surface. Roots grow out of the lower surface and eyes on the upper surface produce the plants. Propagated by division. Includes Iris, Lily of the Valley, Sweet Potato.

Forcing Bulbs

Forcing is done through the fall and early winter for a succession of blooms indoors during the winter months. You will simulate winter by potting up the bulbs and holding them at a temperature between 35 – 50 degrees for the necessary amount of time. Bulbs for forcing include Hardy Narcissus especially Unsurpassable and Quail, tender Narcissus such as Paperwhites, some Tulips, Hyacinths, Crocus, species Iris, Muscari.

Store bulbs in the refrigerator in an open paper bag until you are ready to pot. Do not store them in the fruit bin. Once planted, keep the soil moist but not wet. Store in the refrigerator, a partially heated garage, or a crawl space while the roots develop:

12-14 weeks for Daffodils

14-16 weeks for Tulips

10-12 weeks for Hyacinth

8-10 weeks for Crocus, Dwarf Iris

2-3 weeks for Paperwhites

Bring them into a slightly warmer, brighter location once roots are well formed. The bulbs think it is spring and leaves will begin to grow and extend. When the buds begin to show, the plants can be moved to a sunny spot to continue developing. This second growing period will take 2 weeks for Paperwhites and up to 4 weeks for Tulips.

Paperwhites and Hyacinths can also be grown in a pebble filled decorative container. Put some gravel in the bottom of the container, closely space the bulbs on top of the gravel, then top with remaining gravel to support the bulbs. Add water to just touch the base of the bulbs. Refrigerate for the required time – you will be able to watch the roots grow if you use a glass container.

Galanthus

Hyacinth

Iris, Danford

4” tall, lemon yellow, prefers slightly acis soil.

Iris, Reticulata

4” tall, various shades of blue to purple, prefers alkaline soil.

Leucojem

“Snowflake”, 4-5” nodding white blooms.

Muscari, Armeniacum

“Grape Hyacinth” , Full sun to part shade, plant as soon as received. Blooms in early spring, second set of grass like leaves appears in fall. Purple or white. M. Latifolium – one single wider leaf. Two tone blue and purple flowers.

Narcissus

Long lived, prolific, easy to grow. Part shade to full sun. Plant early. Rodent Proof.

Scillasiberica

Tulip

Full sun but will tolerate part shade. Work the soil deeply and provide good drainiage. Plant as late as possible, store till then at 40-60 degrees. Short lived. Some “perennial” hybrids, species Tulips, and Darwin Hybrids will last for years. Plant 8-10” deep to improve longevity and deter rodents who relish Tulips.

Early Tulips:

Kaufmaniana – Water Lily Tulips. Short stemmed, blooms open wide in the sun and close in the evening.